Ultrasounds During Pregnancy: How Many Should You Have?

Current medical guidelines from the American Congress of Obstetricians and Gynecologists (ACOG) state that low-risk pregnant women may receive one to two ultrasounds during their pregnancy (generally one before 13 weeks to date the pregnancy and one between 16-20 weeks). There is growing inconsistency, however, in the number of ultrasounds advised and the number women actually receive. A new article released Friday in the Wall Street Journal identifies that women receive on agerage 5.2 ultrasound scans per pregnancy (and for many, this number is likely higher). Author and regular WSJ writer Kevin Helliker reviews the most current research available on ultrasound usage and safety, and shares input from key experts in the field. Helliker was inspired to investigate the topic after his own wife went in for her 16th ultrasound during the sixth month of her low-risk pregnancy.

What's wrong with having more (or even unlimited) ultrasounds during your pregnancy if you are low-risk? In the last few years, more evidence that frequent ultrasounds during pregnancy -- especially those without medical evidence -- are unnecessary for low-risk women (which accounts for 80% or more of pregnancies) and in fact, have the potential to cause harm in the way of potential unknown side effects for baby and unnecessary medical interventions during birth. Last year, the U.S. Food and Drug Administration issued a warning against the use of keepsake ultrasound images and videos, like those offered at independent businesses located in malls or strip malls outside of a doctor's office.

What Helliker uncovered is not new information, but rather information and guidance that deserves more attention from both care providers and pregnant families. Fetal ultrasounds have for many years been show to be safe. However, as Helliker writes, "nearly all research supporting its safety was conducted using equipment made before 1992, when the procedure produced about one-eighth the acoustic energy it is allowed to emit today and when fetal-ultrasound scanning was far less frequent."

What this means is that we don't know the longterm effects of fetal ultrasounds with the equipment that's used today, which is significantly more powerful than in earlier years. The FDA delivered a similar warning in its statement last December, and went on to report that "ultrasound can heat tissues slightly, and in some cases, it can also produce very small bubbles (cavitation) in some tissues. The long-term effects of tissue heating and cavitation are not known."

Futhermore, studies are suggesting that ultrasound operators are not paying close attention to safety indicators that appear on the ultrasound screen, which measures temperature increases and "mechanical effects," which could pose risks for tissue and cells. Helliker reports:

Now, some fetal-ultrasound experts say women should be explicitly told that—in the absence of complications or alarms—one or two is sufficient for the average low-risk pregnancy.

“The message needs to be gotten out,” says Phillip J. Bendick, an ultrasound scientist and editor of the Journal of Diagnostic Medical Sonography. “The public needs to be made aware that if you’re pregnant, you don’t drink alcohol, you don’t smoke and you don’t need to have an ultrasound at every doctor’s visit.”

In addition to unknown medical issues multiple ultrasounds may produce, research shows us that they don't provider better outcomes. As Lamaze educators already well know and teach to expectant families, ultrasounds can produce false positives which can lead to unnecessary medical interventions in pregnancy and birth. This is especially true when an ultrasound is performed in the late third trimester and a fetal weight estimate is given. As Helliker shares, "The 2012 American Journal of Obstetrics and Gynecology paper found women who received a fetal-weight estimate via ultrasound within a month of delivery were 44% more likely to be delivered by caesarean section."

Of course, providers and researchers also want families to know that ultrasounds have been proven to have critical benefits. This is especially true for more accurately dating a pregnancy (when ultrasound is performed in the first trimester, between 8-12 weeks), for identifying multiples, and to detect abnormalities that may require early intervention to improve baby's health outcome. Helliker also tells us that "research suggests images of the unborn can help foster bonding, perhaps persuading some pregnant women to quit smoking."

The bottom line? Every pregnancy is different and should be cared for individually. High risk pregnancies may require additional ultrasound scans to improve the health of mom and baby. Low-risk pregnancies do not need any more than 1-2 ultrasounds, and will likely be safer and healthier when additional ultrasounds are avoided. If you are low risk and your care provider recommends an ultrasound, be sure to ask:

Why are you recommending this ultrasound?

How will information from this ultrasound be used?

What are alternatives to an ultrasound?

What are the risks in not receiving an ultrasound?

I encourage you to read the complete article at Wall Street Journal, and to investigate the topic on your own and with your care provider. Becoming a more informed and savvy health care consumer will go a long way to improving your experience, health, safety, and satisfaction!